The elastomeric gaskets utilized to seal doors, trunk lids etc. of vehicles are constructed with a "carrier" portion and an integral "bubble" portion. The carrier portion provides a surface for attachment to the frame surrounding the opening to be closed by the door or lid, and the bubble portion provides for the cushioning action of the gasket. However, to be effective in this cushioning, the bubble portion typically is provided with vent openings at selected spacings along the length of the gasket material. These vent openings are typically produced in the bulk gasket material prior to the forming of gasket elements of a particular configuration. For example, one of the most common vent configuration is a vent size of 0.165 in., and a spacing of 6 inches. In order to have uniformity of action of the gaskets, the specifications for the vents call for very precise hole size and spacing. Typically the size of the hole must be within .+-. 0.005 inches and the spacing must be within .+-.0.015 inches.
In order to produce the vent holes in the bulk gasket material, it has been common practice to feed a continuous body of gasket material through a drilling machine. Typically, this prior art machine has utilized two high-speed drilling units set apart at the given spacing. These drilling units are reciprocated (advanced, and then withdrawn) orbitally at a high rate of speed while the gasket material is fed past the drilling units. Typically about one second is required to drill these two holes. However, even with the high-speed advancing and withdrawing of the drills, the holes often have an oval configuration rather than being round. When this non-uniformity is excessive the material must be discarded. Further, the high speed operation produces significant wear on the components and the drilling units must be overhauled on at least a weekly basis. This requires either a significant "down time" or a plurality of processing lines. When the units are functioning satisfactorily the bulk gasket material can be processed at a maximum of about 60 feet per minute.
Accordingly, it is an object of the present invention to provide a drilling machine to produce uniform openings in strip material.
It is another object of the present invention to provide a drilling machine for producing the vent holes in gasket material wherein the bulk material can be processed at a substantially higher rate than with drilling units of the prior art.
Another object of the present invention is to provide a rotary drilling unit whereby drilling of the vent holes progresses as the gasket material moves through the machine, the drilling achieving round vent holes at a uniform spacing.
A further object of the present invention is to provide a drilling unit thereby maintenance thereof is only at extended periods of operation in contrast to those of the prior art.
These and other objects of the present invention will become apparent upon a consideration of the drawings which follow together with the detailed description thereof in connection with the operation of the invention.